Gas turbine engines, such as those which power aircraft and industrial equipment, employ a compressor to compress air that is drawn into the engine and a turbine to capture energy associated with the combustion of a fuel-air mixture.
One or more cases are used to house the engine sections. For example, an engine case may house the turbine section. From the perspective of engine performance/efficiency, it is desirable to maintain as small a gap/clearance between the static engine case (stator) and the rotating turbine (rotor) blades as possible in order to maximize the energy that is captured by the turbine section as described above. However, a minimum clearance threshold must be maintained; otherwise, the turbine blades and the engine case (or an associated blade outer air seal) may rub against one another so as to reduce the usable lifetime of these components.
Active clearance control (ACC) hardware is used to control the temperature of the engine case. For example, supplying cool air to the engine case causes the engine case to contract, thereby decreasing the clearance between the engine case and the turbine blades. Referring to FIG. 2, an example of an ACC system 200 in accordance with the prior art is shown. In the system 200, bleed air 204 is taken from, e.g., the compressor and is supplied to one or more manifolds (e.g., manifolds 212a and 212b) via an inlet pipe 216 and a collector 218. The manifolds 212a and 212b are located proximate to, e.g., radially outboard of, a high pressure turbine engine case (not shown) and may dispense at least some of the bleed air 204 onto the case. A portion of the bleed air 204 may be conveyed to other portions/sections of the engine via piping/tubing 224.
The interface 232 between the collector 218 and the manifolds 212a and 212b may be susceptible to leaking. A leak may be caused by a movement/deflection of the collector 218 relative to the manifolds 212a and 212b. Such movement/deflection may be based at least in part on loads (e.g., thermal loads, vibratory loads, etc.) experienced by the engine hardware during engine operation. If a leak were to develop, the ACC system 200 may suffer a supply pressure drop that may result in a loss of closure of the ACC system 200.